geometry

Math

Area of a triangle : $1/2\cdot h\cdot b$

Area of circle : $\pi r^2$

Area of a trapezoid : $w\cdot \frac{a+b}{2}$ (w is for the sides that are the same length)

Area of a cylinder : $\pi r^{2}h$

circle w/ center (a,b) and radius r : $(x-a{)}^2+(y-b{)}^2=r^2$